Ettinghausen oversaw BBH Labs, the agency’s global research and development unit, which was set up in 2008 by Mel Exon and Ben Malbon.
Labs is continuing, with strategy director Achim Schauerte taking the reins.
It is not clear what Ettinghausen’s future plans are as he did not provide comment beyond referring questions to BBH.
His departure comes six months after Exon left BBH after two years as managing director, to take up the role of chief executive of The Sunshine Company.
Ettinghausen was one the creatives behind "Clarks unboxed", the multimedia experience launched last year to celebrate 200 years of the brand.